90445781 has 4 divisors (see below), whose sum is σ = 90656064. Its totient is φ = 90235500.

The previous prime is 90445777. The next prime is 90445787. The reversal of 90445781 is 18754409.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 90445781 - 2² = 90445777 is a prime.

It is a super-2 number, since 2×90445781² = 16360878601399922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90445787) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 104495 + ... + 105356.

It is an arithmetic number, because the mean of its divisors is an integer number (22664016).

Almost surely, 2^90445781 is an apocalyptic number.

It is an amenable number.

90445781 is a deficient number, since it is larger than the sum of its proper divisors (210283).

90445781 is a wasteful number, since it uses less digits than its factorization.

90445781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210282.

The product of its (nonzero) digits is 40320, while the sum is 38.

The square root of 90445781 is about 9510.2986809038. The cubic root of 90445781 is about 448.8791545854.

The spelling of 90445781 in words is "ninety million, four hundred forty-five thousand, seven hundred eighty-one".